Hello i'm new to this forum
I am buying a Mountain bike off of craigslist used. I want to switch the V brakes to disc brakes and wondered how do i do that. Can i do it on my own?? are there any instructions here to help me??

Well, I can say that, as with any forum, please use the search function and do some reading before starting a new thread...not trying to sound like a dillhole, but the regulars on forums get pretty irritated with new threads from people that don't search first. Just sayin' Forgive me, but I'm new here myself so I can't link you to how-to.

I can tell you that the frame and fork must be disc brake compatible, you need to be able to mount the calipers to something. You'll need disc-compatible hubs as well, in the very least. If you don't want to/can't rebuild your wheelset, or don't want to pay somebody to do it, then you'll need to pick up a new disc brake-compatible wheelset.

Once you get the basic compatibility requirements down, it's as easy as picking what brakes you want to run, buying them, and installing them.

Again, I wasn't meaning to sound condescending, but I'm a member on a number of other forums and have seen countless individuals get flamed to no end for refusing to search.

Post up the bike you're looking at. Some bikes are ready to go, and all you need are mounts. Others don't have mounts and will need either new wheels (or new disc compatible hubs, which will likely cost just as much as new wheels), a new fork, or a McGyvered mount in the back (or all of the above).

If you want to increase your braking power, change your V-brake pads to Koolstop salmon colored pads. I had them on my Rockhopper and they stopped that bike as quickly as the Avid bb7's that are on there now. Otherwise, I would not invest in Disc brakes for your bike. I'd just ride it like it is.